# include <stdio.h>
int main()
{
	float a='\0';
	printf("enter\n");
	scanf("%f",&a);
	while (a>100 || a<0)
	{
		printf("again enter\n");
		scanf("%f",&a);
	}
	switch (int (a/10))
	{
		case 10:
		case 9:printf("a\n");break;
		case 8:printf("b\n");break;
		case 7:printf("c\n");break;
		case 6:printf("d\n");break;
		default :printf("E! fail!\n");
	}
	return 0;
}
